True Story: Light Headed?

Science
Science brain teasers require understanding of the physical or biological world and the laws that govern it.

After a long day of work, I was relieved. I had been working since 4pm in a circuitry lab, working on the next big project. I observed the sun just starting to descend as I started to walk out to my car. All of a sudden, however, I had an urge to sneeze furiously! If it's the middle of January on a windy day, what's happening here?

Hint

- It's January, so there isn't very much pollen... at least not enough to be the cause.
- I don't have any allergies.
- It's windy, so dust can't really settle anywhere.
- I'm not sick.
- This is a common occurrence for me.
- 20-25% of people will get this teaser right off the bat.

Answer

I have what's called the photic sneeze reflex.

A few people have this quality which makes them sneeze when they are subjected to bright light, like the sun... especially if they are just coming from a darker room or place. About 20-25% of people have the photic sneeze reflex. The funny thing is it's difficult to monitor who has it and who doesn't... because all people who have this reflex tend to assume that all people have it and those who don't have it don't recognize this as a possibility!

You have no idea how many times I've been nailed when I try to explain this one ;-)